Why do people have such a issue with ginger hair?

Hi, im 13 years old and go to high school. Have ginger hair which is often pointed out as i walk through the corridors but that never really bothered me as i know that its just hair and that the people who called "GINGER" are just retards. But the other day we i was walking through town, this 21 (about 21 anyway) year old woman went ginger as she walked past me! Now someone please tell me why they have such a problem!?! i am just as smart, interesting NORMAL as the next person. 13-16 yr olds i exspect but a 20 yr old? Some people need to get a liife.